On 25 May 2009, the DPRK announced it second nuclear test.

25 May 2009 - DPRK II

The greater magnitude of the explosion and the fact that many more stations had been established since 2006 meant that the global alarm system could home in better on the 2009 event than the test announced three years earlier.

During the night of 25 May 2009, at 00:54:43 GMT to be precise, the CTBTO's global alarm system located a seismic event in the north east of the Democratic People's Republic of Korea (DPRK). Twenty-three seismic stations had picked up unambiguous explosion-like signals. The first automatic estimation of time, location and magnitude of the event was made available to CTBTO Member States at 02:24 GMT (read more on the CTBTO's initial findings).

The DPRK's action was denounced universally. CTBTO Executive Secretary Tibor Tóth deplored the "serious violation of the norm established by the Comprehensive Nuclear-Test-Ban Treaty (CTBT)." CTBTO Member States condemned the DPRK's action and urged it to sign and ratify the CTBT. The necessity of the CTBT's entry into force was also emphasized by UN Secretary-General Ban Ki-moon. Eight countries have yet to ratify for the Treaty to enter into force: China, Egypt, Iran, Israel and the United States, who have already signed the treaty, as well as the DPRK, India and Pakistan, who have to both sign and ratify.

The UN Security Council passed Resolution 1874 unanimously. It imposed tighter economic sanctions on the country than Resolution 1718 (2006), allowing UN Member States to inspect any North Korean cargo that might have a connection with the nuclear programme. The Security Council thereby showed consistency in denouncing every nuclear test conducted since the CTBT opened for signature in September 1996 (so including the 2006 DPRK test and the ones conducted by India and Pakistan in May 1998).

Unlike the tests in 2006 and 2013, no radioactive noble gases were detected after the 2009 DPRK event - neither by the CTBTO nor by individual countries using national means. However, experts agreed that a "nuclear bluff" scenario was highly implausible. A definite clarification of the nature of the DPRK event would have been brought about through an on-site inspection had the Treaty already been in force. In this case, the scientific evidence collected by the CTBTO's monitoring stations would have provided a firm basis for a decision by the CTBTO's future Executive Council to dispatch an on-site inspection.

See the DPRK 2013 page for information on the latest nuclear test announced by the country.